Overmolded high strength polymer-based cartridge casing for blank and subsonic ammunition

ABSTRACT

A high strength polymer-based cartridge casing for blank or subsonic ammunition has a reduced volume and includes a mouth, a neck extending away from the mouth, and a shoulder extending below the neck. Additionally, the cartridge includes an extraction rim and a groove, a primer pocket and a flash hole in fluid communication with the reduced volume. An inner wall encloses the reduced volume. The mouth has a first diameter and the inner wall has a second diameter and the second diameter is approximately equal to the first diameter. Further, the neck, shoulder, rim, groove, and inner wall all comprise a polymer. Further, the inner wall can be a metallic sleeve overmolded by a polymer sheath. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. application Ser. No.13/350,585, filed Jan. 13, 2012. The '585 applications claims priorityto U.S. Provisional Application Ser. No. 61/433,170 filed Jan. 14, 2011.Both applications are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present subject matter relates to techniques and equipment to makeammunition articles and, more particularly, to ammunition articles withplastic components such as cartridge casing bodies and bases for atleast blank and subsonic ammunition.

BACKGROUND

It is well known in the industry to manufacture bullets andcorresponding cartridge cases from either brass or steel. Typically,industry design calls for materials that are strong enough to withstandextreme operating pressures and which can be formed into a cartridgecase to hold the bullet, while simultaneously resist rupturing duringthe firing process.

Conventional ammunition typically includes four basic components, thatis, the bullet, the cartridge case holding the bullet therein, apropellant used to push the bullet down the barrel at predeterminedvelocities, and a primer, which provides the spark needed to ignite thepowder which sets the bullet in motion down the barrel.

The cartridge case is typically formed from brass and is configured tohold the bullet therein to create a predetermined resistance, which isknown in the industry as bullet pull. The cartridge case is alsodesigned to contain the propellant media as well as the primer.

However, brass is heavy, expensive, and potentially hazardous. Forexample, the weight of 0.50 caliber ammunition is about 60 pounds perbox (200 cartridges plus links).

The bullet is configured to fit within an open end or mouth of thecartridge case and conventionally includes a groove (hereinafterreferred to as a cannelure) formed in the mid section of the bullet toaccept a crimping action imparted to the metallic cartridge casetherein. When the crimped portion of the cartridge case holds the bulletby locking into the cannelure, a bullet pull value is providedrepresenting a predetermined tension at which the cartridge case holdsthe bullet. The bullet pull value, in effect, assists imparting aregulated pressure and velocity to the bullet when the bullet leaves thecartridge case and travels down the barrel of a gun.

Furthermore, the bullet is typically manufactured from a soft material,such as, for example only, lead, wherein the bullet accepts the mouth ofthe cartridge being crimped to any portion of the bullet to hold thebullet in place in the cartridge case, even though the cartridge case iscrimped to the cannelure of the bullet.

However, one drawback of this design is that the crimped neck does notrelease from around the bullet evenly when fired. This leads touncertain performance from round to round. Pressures can build upunevenly and alter the accuracy of the bullet.

The propellant is typically a solid chemical compound in powder formcommonly referred to as smokeless powder. Propellants are selected suchthat when confined within the cartridge case, the propellant burns at aknown and predictably rapid rate to produce the desired expanding gases.As discussed above, the expanding gases of the propellant provide theenergy force that launches the bullet from the grasp of the cartridgecase and propels the bullet down the barrel of the gun at a known andrelatively high velocity.

The primer is the smallest of the four basic components used to formconventional ammunition. As discussed above, primers provide the sparkneeded to ignite the powder that sets the bullet in motion down thebarrel. The primer includes a relatively small metal cup containing apriming mixture, foil paper, and relatively small metal post, commonlyreferred to as an anvil.

When a firing pin of a gun or firearm strikes a casing of the primer,the anvil is crushed to ignite the priming mixture contained in themetal cup of the primer. Typically, the primer mixture is an explosivelead styphnate blended with non-corrosive fuels and oxidizers whichburns through a flash hole formed in the rear area of the cartridge caseand ignites the propellant stored in the cartridge case. In addition toigniting the propellant, the primer produces an initial pressure tosupport the burning propellant and seals the rear of the cartridge caseto prevent high-pressure gases from escaping rearward. It should benoted that it is well known in the industry to manufacture primers inseveral different sizes and from different mixtures, each of whichaffects ignition differently.

The cartridge case, which is typically metallic, acts as a payloaddelivery vessel and can have several body shapes and headconfigurations, depending on the caliber of the ammunition. Despite thedifferent body shapes and head configurations, all cartridge cases havea feature used to guide the cartridge case, with a bullet held therein,into the chamber of the gun or firearm.

The primary objective of the cartridge case is to hold the bullet,primer, and propellant therein until the gun is fired. Upon firing ofthe gun, the cartridge case seals the chamber to prevent the hot gasesfrom escaping the chamber in a rearward direction and harming theshooter. The empty cartridge case is extracted manually or with theassistance of gas or recoil from the chamber once the gun is fired.

As shown in FIG. 1A, a bottleneck cartridge case 10 has a body 11 formedwith a shoulder 12 that tapers into a neck 13 having a mouth at a firstend. A primer holding chamber 15 is formed at a second end of the bodyopposite the first end. A divider 16 separates a main cartridge caseholding chamber 17, which contains a propellant, from the primer holdingchamber 15, which communicate with each other via a flash hole channel18 formed in the web area 16. An exterior circumferential region of therear end of the cartridge case includes an extraction groove 19 a and arim 19 b.

Prior art patents in this area include U.S. Pat. No. 4,147,107 toRingdal, U.S. Pat. No. 6,845,716 to Husseini et al., U.S. Pat. No.7,213,519 to Wiley et al., and U.S. Pat. No. 7,610,858 to Chung. Thefour patents are directed to an ammunition cartridge suitable for riflesor guns and including a cartridge case made of at least a plasticsmaterial. However, each have their own drawbacks.

Further, the use of brass cartridges for blank or subsonic ammunitioncan be problematic. To reduce the velocity of the bullet exiting thecartridge, typically less propellant is used is comparison to when thebullet is traveling at its top velocity. However, the same sizecartridge needs to be used so the bullet can be fired from a standardfirearm. An empty space is left inside a blank or subsonic cartridgewhere the propellant would normally reside. To compensate, wadding(typically cotton) can be packed into the space normally filled by thepropellant. This wadding can cause problems with the use of the round,including jamming the firearm and fouling silencers and/or suppressorsattached to the firearm.

Hence, a need exists for a polymer casing that can perform as well as orbetter than the brass alternative. A further improvement is polymercasings that are capable of production in a more conventional and costeffective manner, i.e. by using standard loading presses. Additionally,the cartridge can provide increased performance for blank and subsonicrounds.

SUMMARY

The teachings herein alleviate one or more of the above noted problemswith the strength and formation of polymer based cartridges.

A high strength polymer-based cartridge casing for blank or subsonicammunition can have a reduced volume and includes a mouth, a neckextending away from the mouth, and a shoulder extending below the neck.Additionally, the cartridge includes an extraction rim and a groove, aprimer pocket and a flash hole in fluid communication with the reducedvolume. An inner wall encloses the reduced volume. The mouth has a firstdiameter and the inner wall has a second diameter and the seconddiameter is approximately equal to the first diameter. Further, theneck, shoulder, rim, groove, and inner wall all comprise a polymer.

In an example, the reduced volume of the propellant chamber permits onlyenough propellant to propel a bullet engaged in the cartridge casing atsubsonic speeds. Further, the bullet can have a third diameter and thesecond diameter is approximately equal to the third diameter.Additionally, the second diameter can constant over a length of theinner wall, either before or up to the flash hole.

A yet further example of a high strength polymer-based cartridge casingfor blank or subsonic ammunition has an insert with an extraction rimand a groove and a primer pocket with a flash hole in fluidcommunication with the reduced volume. A sleeve section is alsoincluded. The sleeve section can be made of a metal or a metal alloy andhas a mouth to receive a bullet, a neck extending away from the mouth, awall enclosing at least a portion of the reduced volume and a firstdiameter which can be constant over a length of the wall. A polymersheath can be formed over the outer wall of the sleeve section and theinsert. The sheath has a shoulder extending below the neck and anoutside wall extending the length of the sleeve section.

In certain examples, the insert and the sleeve section can be integraland the insert can be made from a metal or a metal alloy. The sleevesection can also have a ridge formed on the wall and a key formed on theridge, both engaging the polymer sheath. In an example the keys can beone of a flat portion, a raised portion, or dimples. Alternate to, orincluding, the sleeve section further comprises knurling. The insert canalso be polymer.

Additional examples include the polymer sheath having a neck extendingaway from the mouth.

Further examples include the polymer sheath having an upper componenthaving the sleeve section and a lower component having the insert, andthe upper and lower components are joined together at anoverlap/underskirt/taper portion.

A yet further example of a high strength polymer-based cartridge casingfor blank or subsonic ammunition can have an insert with an extractionrim, groove, primer pocket, and flash hole. Also, it can include a metalor metal alloy sleeve section with a wall enclosing at least a portionof a reduced volume propellant chamber and having a first diameterconstant over a length of the wall. A polymer sheath can be formed overthe wall of the sleeve section and the insert. The sheath can includethe mouth to receive a bullet and the neck extending away from themouth. The other portions can be similar to the above examples.

As a result, a light weight, high strength cartridge case can be formedusing standard brass cartridge loading equipment. As noted below, thepresent invention can be adapted to any type of cartridge, caliber,powder load, or primer. Calibers can range at least between 0.22 and 30mm and accept any type of bullet that can be loaded in a typical brasscartridge.

Further advantages can be gained in both blank and subsonic ammunitiondue to the removal of wadding and the shrinking of the volume of powderbased on a reduced volume in the cartridge.

The polymer used can be of any known polymer and additives, but thepresent invention uses a nylon polymer with glass fibers. Further, theportion of the cartridge that engages the extractor of the firearm canbe made from heat strengthened steel for normal loads and can be acontinuous molded polymer piece of the lower component for eithersubsonic or blank ammunition.

Additional advantages and novel features will be set forth in part inthe description which follows, and in part will become apparent to thoseskilled in the art upon examination of the following and theaccompanying drawings or may be learned by production or operation ofthe examples. The advantages of the present teachings may be realizedand attained by practice or use of various aspects of the methodologies,instrumentalities and combinations set forth in the detailed examplesdiscussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present teachings, by way of example only, not by way of limitation.In the figures, like reference numerals refer to the same or similarelements.

FIG. 1A is a cross sectional view of a conventional bottleneck cartridgecase;

FIG. 1B is a side view of a conventional bullet;

FIG. 2 is a side perspective view of the outside of cartridge case ofthe present invention;

FIG. 3 is a longitudinal cross-section of the upper component of thecartridge;

FIG. 4 is a bottom, side, perspective, radial cross-section of the upperand lower components of the cartridge;

FIG. 5 is an end view of the upper component without the lower componentand insert;

FIG. 6 is a side view of the lower component without the upper componentand insert;

FIG. 7 is a bottom front perspective view of the lower component of FIG.6;

FIG. 8 is a longitudinal cross-section view of the lower component ofFIG. 6;

FIG. 9 is a side view of the insert without the upper and lowercomponents;

FIG. 10 is a bottom front perspective view of the insert of FIG. 8;

FIG. 11 is a longitudinal cross-section view of the insert of FIG. 8;

FIG. 12 is a longitudinal cross-section view of an example of acartridge case;

FIG. 13 is a top, side, perspective view of the upper component of theexample;

FIG. 14 is a top, side perspective view of an example of an uppercomponent of a subsonic cartridge;

FIG. 15 is a top, side perspective view of an upper component for ablank cartridge;

FIG. 16 is a longitudinal cross-section view of an example of a straightwall cartridge case;

FIG. 17 is a longitudinal cross-section view of the cartridge case ofFIG. 2;

FIG. 18 is a longitudinal cross-section view of an example of aone-piece blank or subsonic cartridge case;

FIG. 19A is a longitudinal cross-section view of an example of ametallic sleeve with a polymer sheath for a blank or subsonic cartridgecase;

FIG. 19B is a side view of an example of the metallic sleeve of FIG.19A;

FIG. 19C is a partial split longitudinal cross-section view of anexample of a polymer neck with the metallic sleeve;

FIG. 20A is a longitudinal cross-section view of an example of atwo-part metallic sleeve with a one-piece blank or subsonic cartridgecase;

FIG. 20B is a longitudinal cross-section view of an example of atwo-part metallic sleeve with a two-piece blank or subsonic cartridgecase; and

FIG. 20C is a longitudinal cross-section view of an example of aone-part metallic sleeve with a one-piece blank or subsonic cartridgecase.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and/or circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

The present invention provides a cartridge case body strong enough towithstand gas pressures that equal or surpass the strength of brasscartridge cases under certain conditions, e.g. for both storage andhandling.

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below. FIG. 2 illustrates an exampleof a cartridge case 100. The cartridge case 100 includes an uppercomponent 200, a lower component 300, and an insert 400. In thisexample, the upper component 200 and the lower component 300 are made ofa polymer, while insert 400 is made from a metal, an alloy of metals, oran alloy of a metal and a non-metal. Regardless of materials, the outerdimensions of the cartridge case 100 are within the acceptabletolerances for whatever caliber firearm it will be loaded into.

The polymer used is lighter than brass. A glass-filled high impactpolymer can be used where the glass content is between 0%-50%,preferably between 5% and 50%. In another example the glass content canbe 10%. An example of a high impact polymer without the glass content isBASF's Capron® BU501. The insert 400 can be made of steel, and, in anexample, heat treated carbon steel, 4140. The 4140 steel is further heattreated to a Rockwell “C” scale (“RC”) hardness of about 20 to about 50.However, any carbon steel with similar properties, other metals, metalalloys or metal/non-metal alloys can be used to form the insert. Heattreating a lower cost steel alloy to improve its strength is a point ofdistinction from the prior art, which have typically opted for moreexpensive alloys to deal with the strength and ductility needed for acartridge casing application.

Further to the above, as noted for the insert, any metal, metal alloy,or non-metal alloys, ranging from the common place (e.g. brass) to theexotic (e.g. ceramics), can be used to form the insert. The mainrequirement is to withstand both the explosive and subsequent extractiveforces subjected to the insert. The ability to form the insert easilyand inexpensively are of a separate consideration. The same holds truefor the polymer, it can be of any type or quality as long as it meetsthe requirements of the specific example noted below.

In an example, the combination of the upper component 200 and the lowercomponent 300 are made of 10% glass-filled high impact polymer combinedwith the insert 400 made of heat treated 4140 steel results in acartridge that is approximately 50% lighter than a brass formedcounterpart. This weight savings in the unloaded cartridge produces aloaded cartridge of between 25%-30% lighter than the loaded brasscartridge depending on the load used, i.e. which bullet, how muchpowder, and type of powder used.

The upper component 200 includes a body 202 which transitions into ashoulder 204 that tapers into a neck 206 having a mouth 208 at a firstend 210. The upper component 200 joins the lower component 300 at anopposite, second end 212. The lower component 300 joins the uppercomponent 200 at a lower component first end 302 (see FIG. 6). The upper200 and lower 300 components are adhered by an ultraviolet (UV) light orheat cured resin, a spin weld, a laser weld or an ultrasonic weld.

At a second end 304 of the lower component 300, the lower component isjoined to the insert 400. In one example, the upper component 200 andthe lower component 300 are molded in separate molds. When the lowercomponent 300 is molded, it is molded over the insert 400. This is apartial molding over, since the lower component 300 does not completelycover the insert 400.

A back end 402 of the insert 400 is also the rear end of the casing 100.The insert 400 is formed with an extraction groove 404 and a rim 406.The groove 404 and rim 406 are dimensioned to the specific size asdictated by the caliber of the ammunition. The insert 400 can be formedby turning down bar stock to the specific dimensions or can be coldformed.

Turning now to FIG. 3, a cross-section of the upper component 200 isillustrated. Because of the nature of the polymer, and the design of theneck 206 and mouth 208, the neck 206 expands uniformly under the gaspressures formed during firing. This concentric expansion provides asmoother release of the projectile into the barrel of the firearm. Thesmoother release allows for a more stable flight of the projectile,providing greater accuracy and distance with the same amount of powder.

Moving toward the second end 212 of the upper component 200, as the neck206 transitions into the shoulder 204, a sleeve 230 begins. The sleeve230, in this example, extends approximately to the second end 212. Thesleeve 230 can be an additional thickness to a wall 218 as is normallyrequired for a standard cartridge, or a separately manufactured andadhered to the wall 218. The sleeve 230 provides additional strengthrelative to the wall 218 of the body 202 alone. This strengthening,which is in the lateral direction, reduces bending of the uppercomponent 200 of the cartridge case 100. The sleeve 230 helps to keepthe cartridge 100 as concentric as possible, and as noted above,concentricity is a key to accuracy.

The case wall 218 can have a thickness T, and the sleeve 230 can have athickness T+, as illustrated in FIG. 4. Thus, the total thickness of thecartridge at the point where there is the wall 218 and sleeve 230 is thesum of T and T+.

The upper portion 220 of the sleeve 230 can begin in or near the neck206 and extend over the shoulder 204. In one example, the upper portion220 of the sleeve 230 ends against a bullet 50 (see FIG. 1B) providingadditional material, and thus strength, to help retain and align thebullet 50. This thickened upper portion 220 can act like an extension ofthe neck 206 farther down into the shoulder. The upper portion 220 is anadvantage over a brass cartridge, since brass cannot be formed in thisway. Thus, the upper portion 220 can act to sit and secure the bullet inthe same place in the cartridge every time.

The sleeve 230, in the illustrated example of FIGS. 3, 4 and 5, extendsalmost the entire length of the body 202. The sleeve 230 stops at anoverlap potion 222 of the upper component 200. The overlap portion 222is the portion of the upper component 200 that engages the lowercomponent 300. The overlap portion 222 has a thinner wall thickness t,or a second thickness, at the second end 212 than the thickness T of thewall 218 (or T and T+) before the overlap portion 222. The secondthickness t tapers toward the outside of the upper component 200 so anouter diameter 224 of the wall 218 remains constant while an innerdiameter 226 of the wall 218 increases. This allows certain examples ofcartridge 100 to maintain a constant outer diameter from below theshoulder 204 to the insert 400. The bottom end 228 of the sleeve 230 isapproximately squared off to provide a square shoulder to keep the upper200 and lower 300 components concentric during assembly.

FIGS. 6-8 illustrate that the lower component 300 has a tapered portion306 starting at the lower component first end 302 and ending at a collar308. The slope of the tapered portion 306 approximately matches theslope of the overlap portion 222 so the two can slide over each other toengage the upper 200 and lower 300 components. The tapered portion 306ends in a flat seat 307. The seat 307 can have a thickness Ts which isabout equal to the thickness of the wall and/or sleeve. This allows thebottom end 228 of the sleeve to sit on the seat 307 when the upper 200and lower 300 components engage. This prevents the bottom end 228 of thesleeve 230 from being exposed. This could allow the gases to exertpressure on the bottom end 228 that can separate the upper 200 from thelower 300 component.

A width of the collar 308 matches the second thickness t, so that theouter diameter of the cartridge 100 remains constant past the transitionpoint between the upper 200 and lower 300 components. Further, athickness of the tapered portion 306 is such that at any point the sumof it with the thickness of the overlap portion 222 is approximatelyequal to the thickness T of the wall 218 or the thicknesses of the wall218 and sleeve 230 (T and T+). As noted above, the tapered portion 306and the overlap portion 222 are bonded together to join the upper 200and lower 300 components.

An inner wall 310 of the lower component 300 can be formed straight. Inthe illustrated example in FIG. 8, the inner wall 310 forms a bowl shapewith a hole 312 at the bottom. The hole 312 is formed as a function ofthe interface between the lower component 300 and the insert 400, andits formation is discussed below. As the inner wall 310 slopes inward toform the bowl shape, it forks and forms an inner bowl 314 and an outersheath 316. The gap 318 that is formed between the inner bowl 314 andthe outer sheath 316 is the space where a portion of the insert 400engages the lower component 300. As noted above, in one example, thelower component 300 is molded over a portion of the insert 400 to jointhe two parts.

Turning now to an example of the insert 400, as illustrated in FIG. 9,it includes an overmolded area 408, where the outer sheath 316 engagesthe insert 400 in the gap 318. The overmolded area 408 has one or moreridges 410. The ridges 410 allow the polymer from the outer sheath 316,during molding, to forms bands 320 (see, FIG. 8) in the gap 318. Thecombination of the ridges 410 and bands 320 aid in resisting separationbetween the insert 400 and the lower component 300. The resistance ismost important during the extraction of the cartridge from the firearmby an extractor (not illustrated).

The overmolded area 408 also includes one or more keys 412. The keys 412are flat surfaces on the ridges 410. These keys 412 prevent the insert400 and the lower portion 300 from rotating in relation to one another,i.e. the insert 400 twisting around in the lower portion 300.

Below the overmolded area 408, toward the back end 402, is a selfreinforced area 414. This portion extends to the back end 402 of theinsert 400 and includes the extraction groove 404 and rim 406. The selfreinforced area 414 must, solely by the strength of its materials,withstand the forces exerted by the pressures generated by the gasseswhen firing the bullet and the forces generated by the extractor. In thepresent example, the self reinforced area 414 withstands these forcesbecause it is made of a heat treated metal or a metal/non-metal alloy.

FIGS. 10 and 11 illustrate an example of the inside of the insert 400.Open along a portion of the back end 402 and continuing partially towardthe overmolded area 408 is a primer pocket 416. The primer pocket 416 isdimensioned according to the standards for caliber of the cartridge caseand intended use. A primer (not illustrated) is seated in the primerpocket 416, and, as described above, when stricken causes an explosiveforce that ignites the powder (not illustrated) present in the upper 200and lower 300 components.

Forward of the primer pocket 416 is a flash hole 418. Again, the flashhole 418 is dimensioned according to the standards for the caliber ofthe cartridge case and intended use. The flash hole 418 allows theexplosive force of the primer, seated in the primer pocket 418, tocommunicate with the upper 200 and lower 300 components.

Forward of the primer pocket 416 and inside the overmolded area 408 isbasin 420. The basin 420 is adjacent to and outside of the inner bowl314 of the lower component 300. The basin 420 is bowl shaped, whereinthe walls curve inwards toward the bottom. The bottom of the basin 420is interrupted by a ring 422. The ring 422 surrounds the flash hole 418and extends into the basin 420. It is the presence of the ring 422 thatforms the hole 312 in the inner bowl 314 of the lower component 300.

In another example of a cartridge case 120, the sizes of the upper 200and lower 300 components can be altered. FIG. 12 illustrates a “smallupper” embodiment with a bullet 50 in the mouth 208 of the cartridge120. The features of the upper 200 and lower 300 component are almostidentical to the example discussed above, and the insert 400 can beidentical. FIG. 12 also illustrates the engagement between a lip 214 andthe cannelure 55. The lip 214 is a section of the neck 206 approximateto the mouth 208 that has a thicker cross section or, said differently,a portion having a smaller inner diameter than the remainder of the neck206. In this example, the lip 214 is square or rectangular shaped, noangles or curves in the longitudinal direction. Note, in other examples,the upper component 200 is not formed with a lip 214. When present, thelip 214 engages the cannelure 55 formed along an outer circumferentialsurface of the bullet 50 when it is fitted into the mouth 208 of thecartridge casing 100.

FIG. 13 shows that the neck 206 and the shoulder 204 are formed similar,but in this example, the body 202 is much shorter. Further, instead ofan overlap portion 222, there is an underskirt portion 240 that startsvery close to the shoulder 204. The underskirt portion 240 tapers to theinside of the cartridge when it engages the lower component 300.

The lower component 300 in this further example, is now much longer andcomprises most of the propellant chamber 340. The tapered portion is nowreplaced with an outer tapered portion 342. The outer tapered portion342 slides over the underskirt portion 240 so the two can be joinedtogether as noted above. The thickness of the underskirt portion 240 andthe outer tapered portion 342 is approximate to the wall thickness orwall thickness and sleeve thickness.

The inner wall 310 is now substantially longer, can include a sleeve,but still ends in the inner bowl 314. The engagement between the secondend 304 of the lower component 300 and the insert 400 remains the same.Note that either the “small upper” or “long upper” can be used to formblank or subsonic ammunition. The walls are made thicker with thesleeve, shrinking the size of the propellant chamber 340. Less powdercan be used, but the powder is packed similarly as tight as it is for alive round because of the smaller chamber 340. This can prevent theSecondary Explosive Effect (SEE) (below). A thick wall design for asubsonic cartridge 140 is illustrated in FIG. 14.

Illustrated is a large upper component 200 having a thicker overlap 222portion, with a thickness t+ and an integral thickening of the wall,and/or a sleeve 230 with a thickness T+, as disclosed above. The totalthickness of the wall 218 can be the sum of T+ and t+. The sleeve 230can run the length of the upper component 200 from the mouth 208 to thestart of the overlap portion 222. The lower component 300 of a subsoniccartridge 140 can be thickened as well. The subsonic cartridge 140 canbe made with the insert 400, or the lower component 300 can be molded inone piece from polymer with the features of the insert 400. For example,the flash hole 418, primer pocket 416, groove 404 and rim 406.Alternately, the insert can also be high-strength polymer instead of themetal alloys discussed above. In this example, the lower component andthe insert can be formed as one piece, and the upper component 200 canbe placed on top.

As illustrated in FIG. 15, for a blank cartridge 150, the uppercomponent 200 can be made differently. For the blank cartridge 150, anextension 242 can be molded to extend from the neck 206. The extension242 has a star-shaped cap 244 to seal off the cartridge. The cap 244 isformed partially of radially spaced fingers 246 that deform outwardsduring firing. Thus, the mouth 208 is molded partially shut to contain amajority of the pressures and expand open and outwards. The fingers 246are designed, in one example, to be bend elastically and are notfrangible. The object is to contain the majority of the pressures andexpel anything that can act as a projectile out the barrel of thefirearm.

When the blank cartridge 150 is formed with the “small upper” component200 with the cap 244. The lower component 300 can be filled with thepowder and the small upper component can act as a cap to the cartridge,sealing in the powder.

Note that the above examples illustrate a bottleneck cartridge. Many ofthe features above can be used with any cartridge style, includingstraight wall cartridges used in pistols. FIG. 16 illustrates an exampleof a straight wall cartridge 500. The straight wall cartridge 500 is aone-piece design of all polymer. The cartridge 500 has a body 502 and amouth 508 at a first end 510. The walls 518 of the cartridge casing canalso have a sleeve 530 along a majority of its length.

The sleeve 230, 530 is dimensioned and shaped pursuant to therequirements of each cartridge based on blank or subsonic and theparticular caliber. To that end, the sleeve 530 begins set back from thefirst end 510 based on the depth the rear of the bullet sits in thecartridge. Further, in this example, as the walls transition into alower bowl 514, the sleeve 530 may extend into the bowl. This aids inthe strength of a back end 512 of the cartridge 500, since this examplelacks a hardened metal insert.

The lower bowl 514 curves downward toward a flash hole 517 which thenopens to a primer pocket 519. Both are similar to the features describedabove. Further, the back end is molded to form a rim 506.

Turning now to an example of a fully formed cartridge case 100, FIG. 17illustrates a cross-section of all three elements engaged together toillustrate how they interface with each other. The specific outerdimensions of the three elements and certain inner dimensions (e.g.mouth 208, lip 214, flash hole 418, and primer pocket 416) are dictatedby the caliber and type of the firearm and type of ammunition. Thecartridge casing 100 of the present invention is designed to be used forany and all types of firearms and calibers, including pistols, rifles,manual, semi-automatic, and automatic firearms.

An exemplary construction of the upper component 200 also aids inwithstanding the pressures generated. As noted above, the sleeve 230increases the strength of the wall 218 of the upper component 200. Inthe present example, the upper component 200 accounts for anywhere from70% to 90% of the length of the cartridge casing 100.

The polymer construction of the cartridge case also provides a featureof reduced friction between the cartridge and chamber of the firearm.Reduced friction leads to reduced wear on the chamber, further extendingits service life.

Turning now to FIG. 18, an example of a one-piece subsonic cartridgecasing 600 is illustrated. In this example, the entire cartridge casing600 is polymer. The subsonic cartridge casing 600 includes a body 602which, at a first end 610 transitions into a shoulder 604 that tapers onthe outside into a neck 606 having a mouth 608. The bullet 50 can beinserted into the mouth 608 of the subsonic cartridge casing 600.

Opposite the first end 610 is second end 612. A back end 614 is the rearof the second end 612 of the subsonic cartridge casing 600. The back end614 is formed with an extraction groove 616 and a rim 618. The groove616 and rim 618 are dimensioned to the specific size as dictated by thecaliber of the ammunition. Also, included in the back end 614 is aprimer pocket 620. The primer pocket 620 is dimensioned according to thestandards for caliber of the cartridge case and intended use. Forward ofthe primer pocket 620 is a flash hole 622. Again, the flash hole 622 canbe dimensioned according to the standards for the caliber of thecartridge case and intended use. The flash hole 622 allows the explosiveforce of the primer, seated in the primer pocket 620, to communicatewith a propellant chamber 624.

In this example, the propellant chamber 624 is formed from the innerwall 626 of the body 602. The inner wall 626 can be straight from themouth 608 to the back end 214. Thus, a first diameter 628 of the insideof the mouth 608 is approximately equal to a second diameter 630 of thepropellant chamber 624. Alternately, or in addition to, the firstdiameter 628 can be a diameter of the inside of the neck 606.

An outside wall 632 of the body 602 is shaped and dimensioned accordingto the standards for the caliber of the cartridge case and intended use.This includes the length of the neck, the angle of the shoulders, andlength of the total body. A straight inner wall 626 acts to thicken thewalls of the cartridge 600, providing the benefits as described above.The thickened walls act to reduce the size of the propellant chamber624, allowing less powder to be used. In certain examples this cangenerate lower pressures on ignition and expel the bullet 50 at subsonicspeeds.

The straight inside wall 626 example makes for ease of molding. A single“pin” or mandrel can be set to mold a constant diameter from mouth/neck608, 606 to back end 614. The back end 614 can also be made of polymer.Since examples of the cartridge 600 are designed to generate lowerpressures, certain calibers or designs do not require the insert 400, asdescribed above.

In other examples, the subsonic cartridge casing 600 can be eitherformed from 2 or 3 parts. In one example, the back end 614 is replacedwith the overmolded insert 400. In another example, the subsoniccartridge casing 600 can be formed from two pieces, an upper and lowercomponent similar to that described above. However, the components havea constant second diameter 630 between the two. The lower component canbe formed either with the insert or without and the back end 614 ispolymer.

FIGS. 19A and 19B illustrate a further example of a subsonic cartridge700. In this example, a full metal sleeve 702 extends a significantlength of the cartridge 700. The sleeve 702 can have an insert section704 similar to the insert 400, and the sleeve 702 can act as an integralextension of the insert 400. The insert section 704 can have a selfreinforced area 714 which can include an extraction groove 705 and a rim706. The groove 705 and rim 706 are dimensioned to the specific size asdictated by the caliber of the ammunition. The insert section can alsohave a primer pocket 716 and flash hole 718.

Forward of the insert section 704 is sleeve section 708. The sleevesection 708 can extend the length of the cartridge 700 and, in oneexample, form a neck 710 of the cartridge with a mouth 712 wherein thebullet 50 is fitted into the mouth 712. The mouth 712 can have a mouthdiameter 720 sized to receive the bullet 50 and the remaining portion ofthe sleeve section 708 can have a sleeve diameter 722 approximatelyequal to the mouth diameter 720. The sleeve section 708 can act as apropellant chamber 724, and the sleeve diameter 722 can be such as tolimit the amount of propellant so the bullet 50 can travel at subsonicspeeds.

In an example, the sleeve 702 is straight walled and the sleeve diameter722 approximates a bullet diameter 51. To allow the cartridge 700 to fitin a standard chamber for the particular caliber, the outside of thesleeve 702 is molded with a polymer sheath 800. The polymer sheath 800can be molded to the true dimensions of the cartridge for the particularcaliber, including a shoulder 802 and outside wall 804. Multiple ridges726 can be formed in the sleeve section 708 to allow the polymer fromthe polymer sheath 800, during molding, to forms bands (not illustratedand as above). The combination of the ridges 726 and bands aid inresisting separation between the sleeve 700 and the polymer sheath 800.The resistance can be most important during the extraction of thecartridge from the firearm by an extractor (not illustrated).

The ridges 726 can also include one or more keys 728. The keys 728 areflat surfaces on the ridges 726. The keys 728 prevent the sleeve 702 andthe polymer sheath 800 from rotating in relation to one another, i.e.the sleeve 702 twisting around in the polymer sheath 800. Instead of, orin conjunction with, the ridges 726, the sleeve 702 can have knurling ortexturing 730 to prevent the relational rotation.

In other examples, the sleeve section 702 does not extend the length ofthe cartridge 700. The sleeve section 702 can stop at or before themolded shoulder 802. In this example, the polymer sheath 800 can form apolymer neck 806 and polymer mouth 808 to receive the bullet 50. SeeFIG. 19C.

The sleeve 702 can be metal and formed by turning down bar stock to thespecific dimensions or can be cold formed. Further, it can be adifferent metal than the insert section 704. The goal is to create alightweight cartridge using the strength of the metal sleeve and the lowweight, high strength properties of polymers. Using more polymer thanmetal assists in the weight to strength ratio. The polymer sheath 800can be made of the same polymers discussed above or other polymers oflower strength, owing to the metallic support of the sleeve 702. Themetals can be any known metals that can provide light weight strengthunder exploding propellant conditions. This includes brass, aluminum,steel or other alloys. Further, ceramics or other materials may also beused.

In one example, the sleeve 702 can be a brass cartridge from a differentcaliber (typically smaller) that receives a polymer sheath to fit in alarger caliber chamber. The brass cartridge can also be cut or stretchedto accommodate the larger caliber bullet and the particular lengthrequired of the cartridge. Note that in a further example, the sleeve702 can have sloped shoulders and the shoulders can remain exposed orsheathed in polymer. In other examples, the insert section 704 and thesleeve section 708 are not integral. They can be separated and molded asone piece, as in FIG. 20A. Alternately, the examples above can have alower component 900 of polymer 902 and the insert section 704 polymerwelded to an upper component 904 of polymer and sleeve section 708. Theupper and lower components 900, 904 can have a matingoverlap/underskirt/taper section 906, as described above. Eithercomponent 900, 904 can have an overlap or underskirt portion and theopposite component 900, 904 can have the mating taper portion. See FIG.20B. The lower and upper components 900, 904 can be similar to the lowerand upper components described above in assembly and size. FIG. 20Cillustrates the sleeve 702 without the insert section 704, only thesleeve section 708. In this example, the polymer sheath 800 forms a backend 814, similar to the polymer back end 614 described above.

Subsonic ammunition can be manufactured using the above illustratedexamples. Subsonic ammunition is designed to keep the bullet frombreaking the speed of sound (approximately 340 m/s at sea level or lessthan 1,100 fps). Breaking the speed of sound results in the loud “crack”of a sonic boom, thus subsonic ammunition is much quieter than isstandard counterpart. Typical subsonic ammunition uses less powder, toproduce less energy, in the same cartridge case as standard ammunition.The remaining space is packed with wadding/filler to keep the powdernear the flash hole so it can be ignited by the primer. As noted above,increasing the wall thickness eliminates the need for wadding. In oneexample, while a brass cartridge wall can be 0.0389″ thick, the polymerwall and sleeve can have a total thickness of 0.0879″ for the identicalcaliber.

The reduced capacity allows for a more efficient ignition of the powderand a higher load density with less powder. Low load density (roughlybelow 30-40%) is one of the main contributors to the Secondary ExplosiveEffect (SEE). SEE can destroy the strongest rifle action and it canhappen on the first shot or the tenth. SEE is the result of slow orincomplete ignition of small amounts of smokeless powder. The powdersmolders and releases explosive gases which, when finally ignited,detonate in a high order explosion. The better sealing effect is alsoimportant here because standard brass does not seal the chamber well atthe lower pressures created during subsonic shooting.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that the teachings may beapplied in numerous applications, only some of which have been describedherein. It is intended by the following claims to claim any and allapplications, modifications and variations that fall within the truescope of the present teachings.

What is claimed is:
 1. A high strength polymer-based cartridge casingfor at least one of blank or subsonic ammunition inclosing a reducedvolume comprising: a first end comprising a mouth; a neck extending awayfrom the mouth; a shoulder extending below the neck and away from thefirst end; a second end, opposite the first end, comprising: anextraction rim and a groove; and a primer pocket in fluid communicationwith a flash hole, the flash hole in fluid communication with thereduced volume; and an inner wall, extending between the first end andthe second end, enclosing the reduced volume; wherein the mouth has afirst diameter and the inner wall has a second diameter and the seconddiameter is approximately equal to the first diameter, and wherein theneck, shoulder, rim, groove, and inner wall all comprise a polymer. 2.The high strength polymer-based cartridge casing of claim 1, wherein thereduced volume of the propellant chamber permits only enough propellantto propel a bullet engaged in the cartridge casing at subsonic speeds.3. The high strength polymer-based cartridge casing of claim 2, whereinthe bullet comprises a third diameter and the second diameter isapproximately equal to the third diameter.
 4. The high strengthpolymer-based cartridge casing of claim 1, wherein the second diameteris constant over a length of the inner wall until the second end.
 5. Thehigh strength polymer-based cartridge casing of claim 1, wherein thesecond diameter is constant over a length of the inner wall until theflash hole.
 6. A high strength polymer-based cartridge casing for atleast one of blank or subsonic ammunition inclosing a reduced volumecomprising: an insert comprising: an extraction rim and a groove bothdisposed at one end of the insert; and a primer pocket in fluidcommunication with a flash hole, the flash hole in fluid communicationwith the reduced volume; a sleeve section, comprising a metal or a metalalloy, and further comprising: a first end comprising a mouth to receivea bullet; a neck extending away from the mouth; a second end oppositethe first end; a wall extending between the first end and the secondend, enclosing at least a portion of the reduced volume; and a firstdiameter approximately constant over a length of the wall; a polymersheath formed over the wall of the sleeve section and the insert,comprising: a shoulder extending below the neck and away from the firstend; and an outside wall extending the length of the sleeve section. 7.The high strength polymer-based cartridge casing of claim 6, wherein theinsert and the sleeve section are integral and the insert is a metal ora metal alloy.
 8. The high strength polymer-based cartridge casing ofclaim 6, wherein the sleeve section further comprises: a ridge formed onthe wall; and a key formed on the ridge; wherein both the ridge and thekey engage the polymer sheath, and wherein the key comprises at leastone of a flat portion, a raised portion, or dimples.
 9. The highstrength polymer-based cartridge casing of claim 6, wherein the sleevesection further comprises knurling.
 10. The high strength polymer-basedcartridge casing of claim 6, wherein the insert is polymer.
 11. The highstrength polymer-based cartridge casing of claim 6, wherein the polymersheath further comprises a neck extending away from the mouth.
 12. Thehigh strength polymer-based cartridge casing of claim 6, wherein thepolymer sheath further comprises: an upper component comprising thesleeve section; and a lower component comprising the insert, wherein theupper component and lower component are joined together at anoverlap/underskirt/taper portion.
 13. The high strength polymer-basedcartridge casing of claim 6, wherein the reduced volume based on thefirst diameter permits only enough propellant to propel the bulletengaged in the cartridge casing at subsonic speeds.
 14. A high strengthpolymer-based cartridge casing for at least one of blank or subsonicammunition inclosing a reduced volume comprising: an insert comprising:an extraction rim and a groove both disposed at one end of the insert;and a primer pocket in fluid communication with a flash hole, the flashhole in fluid communication with the reduced volume; a sleeve section,comprising a metal or a metal alloy, and further comprising: a first endand a second end opposite the first end; a wall extending between thefirst end and the second end, enclosing at least a portion of thereduced volume; and a first diameter constant over a length of the wall;a polymer sheath formed over the wall of the sleeve section and theinsert, comprising: a mouth to receive a bullet; a neck extending awayfrom the mouth; a shoulder extending below the neck and away from thefirst end; and an outside wall extending the length of the sleevesection.
 15. The high strength polymer-based cartridge casing of claim14, wherein the insert and the sleeve section are integral and theinsert is a metal or a metal alloy.
 16. The high strength polymer-basedcartridge casing of claim 14, wherein the sleeve section furthercomprises: a ridge formed on the wall; and a key formed on the ridge;wherein both the ridge and the key engage the polymer sheath, andwherein the key comprises at least one of a flat portion, a raisedportion, or dimples.
 17. The high strength polymer-based cartridgecasing of claim 14, wherein the sleeve section further comprisesknurling.
 18. The high strength polymer-based cartridge casing of claim14, wherein the insert is polymer.
 19. The high strength polymer-basedcartridge casing of claim 14, wherein the polymer sheath furthercomprises a neck extending away from the mouth.
 20. The high strengthpolymer-based cartridge casing of claim 14, wherein the polymer sheathfurther comprises: an upper component comprising the sleeve section; anda lower component comprising the insert, wherein the upper component andlower component are joined together at an overlap/underskirt/taperportion.
 21. The high strength polymer-based cartridge casing of claim14, wherein the reduced volume based on the first diameter permits onlyenough propellant to propel the bullet engaged in the cartridge casingat subsonic speeds.